Drive mechanism



May 7, 1957 R. A. MALONEY DRIVE MECHANISM Filed Aug. 9 1951 -4Sheets-Sheet 1 16) ROBERT A. MALONEY WK w m ENTOR May 7, 1957 Filed Aug.9 1951 R. A. MALONEY DRIVE MECHANISM 4 Sheets-Sheet 2 INVENTOR ROBERT A.MALONEY R. A. MALONEY' DRIVE MECHANISM May 7, 1957 4 Sheets-Sheet 3Filed Aug. 9, 1951 INVENTOR ROBERT A.MALONEY 16.0.4441 a ZM J May 7,1957 R. A. MALONEY 2,791,648

DRIVE MECHANISM Filed Aug. 9, 1951 4 Sheets-Sheet 4 J g. I 11 .5.

33 INVENTOR ROBERT A. MALONEY United States Patent 2,791,648 DRIVEMECHANISM Robert A. Maloney, Canousburg, Pa., assignor, by mesneassignments, to McGraw-Edison Company, a corporation of DelawareApplication August 9, 1951, Serial No. 241,145 26 Claims. (Cl. 200-18)This invention relates to a new kind of drive mechanism which isrelatively silent and cushioned in operation and in which fewerprincipal or massive parts are accelerated or moved at a higher speed.In particular, this invention pertains to a novel drive mechanismsuitable for switch gear such as those used in load ratio control orstep voltage regulator equipment.

A variety of electrical equipment is used to maintain voltage of theload in electrical systems. A number of these devices include tapchanging under load and many, particularly those having lower rating,are frequently fully automatic and employ high-speed switching betweenthe respective contacts or transformer taps in the circuit. Further, inthe lower ratings, the switching equipment may also perform the currentinterrupting service. In order to obtain relatively high-speed tapchanging in such circuits, many prior drive mechanisms heretofore used,employed springs for snap action and in this employment many of theprincipal or massive parts of the drive had to move at high speed in thecourse of the snap action portion of the cycle with attendant noise andshock. The ditficulty was increased when the device was substantiallymoving at its greatest speed near the end of its travel. Such drivestherefore frequently required relatively expensive alloys forconstruction and greater power for equivalent average speed ofoperation. Such tap changer drives were also used with equipment havinghigher kv.-a. and current ratings although at such higher ratings theuse of separate circuit breakers for current interruption in the circuitis more common. Many of these devices have reversing gear by means ofwhich the same winding can be employed both in opposing and inaugmenting the line voltage under control, whether single phase orpolyphase voltage control.

In this invention, a new kind of drive mechanism for voltage controlswitch gear is provided which overcomes the foregoing difliculties ofprior devices. In the new construction of this invention, a snap actionis obtained with relatively low speed operation of many principal ormassive parts. The result is far quieter operation, less strain on theequipment, longer life and improved performance. Control of thespeed-time action is obtainable with a device made under this inventionwith relatively more rapid breaking of the are and less rapid speed nearthe end of the travel of the device. Further, in this new constructioncushioning means are provided as well as a symmetry of structure whichmarkedly minimizes any tendency to dynamic imbalance. A reversingarrangement may be included which is positive in operation and providesfor opposition or augmentation of the supply voltage.

Other objects and advantages of this invention will be apparent from thefollowing description and from the drawings, which are illustrativeonly, in which:

Figure 1 is an end view of one embodiment of the new drive mechanism ofthis invention with a portion thereof broken away;

Figure 2 is a view taken generally along line 11-11 of Figure 1 with, inaddition, a schematic showing in section of a tap changing and reversingswitch gear arrangement;

Figure 3 is a view on a somewhat reduced scale of the last-mentionedaddition only taken along line III-III of Figure 2;

Figure 4 is a view on a somewhat reduced scale taken along line IV-IV ofFigure 2 with the intermittentmotion gear at rest;

Figure 5 is a view similar to Figure 4 as the intermittent-motion gearis being moved and is passing through its reference position from theposition shown in Figure Figure 6 is a view similar to Figure 4 afterthe intermittent-motion gear has been still further moved from theposition shown in Figures 4 and 5 and has come again to rest;

Figure 7 is a view in elevation of the other side of theintermittent-motion gear in the reference position shown in Figure 5showing a reversing arrangement;

Figure 8 is a view similar to that shown in Figure 7 with theintermittent-motion gear in the position shown in Figure 6;

Figure 9 is an end view of the threaded coupling shown in Figure 2 andits arm taken along line IX-IX of Figure 2;

Figure 10 is a side view of the threaded coupling and arm shown inFigure 9; and

Figure 11 is a view partly in section of a modified spring retainermechanism.

Referring to the drawings, a plate 10 of metal may be bent into the formof an angle to serve as a supporting shelf for the new drive mechanismof this invention. If, for example, the new drive mechanism is to beused inside the tank of a power transformer, plate 10 may be supportedon and bolted to angles 11 forming a structural portion of the interiorof the transformer tank. Angle pieces 12 may also be provided at theupper edge of plate 10 to complete the supporting attachment of the newmechanism to the structure with which it is to be used. Side plates 13are welded to plate 10 and brackets 14 in turn are welded to plates 13.A rigid bar 15 extends between the brackets 14 and is bolted thereto.Pads 16 are welded to the bottom of plate 10 on the inside of the angle.

A conventional prime mover 17 may be bolted to the pads 16 and thusafiixed to plate 10. Prime mover 17 may comprise a reversible electricmotor 18 firmly mounted on and fastened to a casting 19 within whichthere is provided a conventional gear reducing mechanism 20. The primemover 17 is enclosed in such a manner that it may be submerged in thedielectric liquid, such as transformer oil, if the new mechanism of thisinvention is used in a liquid-type transformer. A short shaft 21 extendsfrom the casing of gear reducer 20. A hand crank may be used to turnshaft 21 and thereby operate as a prime mover to cause the new drivemechanism of this invention to function. Ordinarily, the new mechanismwill be operated electrically by means of any of the many circuitsavailable for tap changers in the load ratio control field. Suchcircuits, which need not be illustrated here, may be so arranged as tobe fully automatic or manual in the sense that push buttons are used,for example, to control the electrical circuit to which the new drivemechanism is connected through leads 22 of motor 18. In addition, suchan electrical control circuit whether automatic, semi-automatic ormanual or a combination of these may include limit switches ormechanical steps or both to limit the angular rotation in eitherdirection of the mechanism with which the new drive of this invention isused.

A conventional tap changer for step voltage regulation,

ta cts extend, for example, through panel 23 and haveleads connectedthereto on the other side thereof. An annularly spaced pair of movablecontactslo may coact withthefixed contacts 24. inboth symmetrical andbridging positions to effect step voltage regulation as the movablecontacts 26 are moved by a contact shaft- 27 whic thev e ou t d; Each iping 2,3: audits ush 2 ake a n epen n e ectrical conneetiemwnh.

its'r espective movable contact 26.

In one form of tap, changing apparatus when both 195131 ?On l6= n contawi h fix d onta t Zea. l or 1letl ymm t alpo ition he apparatu is,regarded as being in its single electrical neutral position. It is atthat time. that movable contact, 34 is rotated into contact with theother. of the fixed contacts 25 sothat no current is interrupted and atthe same timethe regulation transformer windings are reversed in thecircuit so asto prepare it for a contrary regulatronactron.

That is if the tap changer had been moving to boost line voltage, theactionresulting from throwing movable con tact 30 to the otherfixedco'ntact ZS Would,,for the. same direction of movement of the equipment,buck the line voltagethereafter, and vice versa Movable. switchcontactSilis carried on an auxiliary contact shaft 31. Both shafts ZZ and 31may be connected. by flexible couplings 32a and 32b respectively tocoupling shaftsZT/a and 31a respectively.

To return to the new drivermechanism, an-output shaft 33 from gearreducer 241 extends toward plate 10. A bearing 34, properly bushed,supports the. other, end of shaft 33. asit is turnedineither directionunder the influence of motor 18 or under the influence of ahand crankturning shaft 21. Asleeve 35 whi ch maybe a casting orfor ged metalshapefitsover shaft33- and is keyed thereto, "lhe sleeVeElS Comprises acam 36 at-the end and .a pinion 37, at the other. Although as. shownthese parts are integral, they may be separately made and keyed totheshaft 33. Cam36 is .ofi a,drum type and is provided with a riseportion 36a and afallpoition 36b,

by means of theexte nt of the respective peripheral portions of which asuitable timing "sequence of the new drive mechanisrnis obtained, Theahgnlarposition of cam 36 on shaft 33" is symmetrical relativeto theangular position of apin 38'whenthe-action of the .new,mecha nism isreversible, as .may norr11al1y ,b.e-the. case.

Pinion 3'73comprises tw. o spaced integral annular flanges 37a and 37b;The pin 33 connects thetwo fianges atv the Z appropriate, angular.position corresponding; to, the angular setting on shaft 33fof cam-36,andofthe respective positions of the electrical contacts in the tapchanger. previously described. A roller 39.is ,rotatably mounted on pin38; for engagement with the sides of recesses 40,

extending radially and in spacedrelation around the periphery of anintermittent-motion rotary plate or gear 41 which may be of theGenevatype. Teeth 42cf gear 4ll=between therecesses Aware provided at their.crests with depressed portions. 43j of concave arcuatenature whichmay betermed saddles. A hub 44 ...ofpinion57 which is integraltherewithisshown-incross. section in Figures-4 to 6" and provides meansfor lockinggear infest position between operatiye engagements of-roller 39 and'theside of any tooth 42 of gear', 41, as illustrated;

Suitable. washersmay by a roller 47. Roller 47 in turn is rotatablymounted on the rear side of gear 41. The lower side of arm 45 isprovided with an arcuate 5101243 to provide a lost motion action betweenarm 45 and a pin 49 on a throw lever 50. When assembled, pin 49 extendsinto opening 48 at all times. An integral journal 51 is provided onlever 50 and is rotatably supported in a bearing 52 in plate It the saidbearing being, suitably hushed.

A sleeve 53 is keyed to the rear end of journal 51. In turn, the.forward end of: coupling; shaft: 31a is connected to sleeve 53. forrotation. Thereby; movement of throw lever 50 to one side or the otherwill move movable contact'30 of thereversing switch arrangemcntifrom onefixed contact 25 to the other but movable contact 39 will not stopbetween. the contacts 25 becauseof the lost mo tion characteristic ofthe arcuate slot 48 even though gear 41 is in its reference position asshown in Figure 5. In that; reference,- position, roller 47 hasenteredslot 4% bringing locking-pins 54 into horizontal alignment andcontinuation of the movement of gear in the same-direction. will; rock:arm. 4-5 into the position, shown in Figure 8. to effect, through pin49, a throw over of movable, contact 30 to the. other fixed contact 25.The reference position shown in Figures 5 and 7 is located aboutrnidway;of. the reference positionmovement sector defined-by the radii.hisecting the saddles 43; immediately on each; side of the roller 47. Inthe; illustrated embodimenhgear. 41. is provided witheighteen teeth 42.and isintended to be;capable of substantially two fullrevoluw tionsineither. direction between its limits of rotational movement. In;addition,- there-are 9 fixed contacts 24 for aboutsixteen steps-ineither direction since the contactslfi; are; operative bothiii-symmetrical position on a single. contactldpther;thancontact 24a andin abridging position bridging two. contacts- 24. The direction; ofmovement. of. contacts .26,will correspond, to the direction of,movement of the gear 41; The reference position movement, sector. inturn. occurs, about halfway through thesubstantially twofullrevolutionsof gear 41 which may be provid-ed in .eitherone direction between itsusual limits ofmovement for theillustratedembodiment. ln generaLthenew.mechanism will be. so assembled that thfe switching ofnn'ovable contact3%) from the fixed-contact 2 5 onwhieh it is, resting to the other fixedcontact. 25 will tale-e place. during. movement; of the gear: lr thrhjheareference position movementsector and will substantiallybecompletedbefore either movahlecontact 2 6,' as .th e. case maybe,leaves fixed contact 24a;

As shown in ,Eigures 7 and 8, an inner annular locking afisfiii tld m trl ev 56e JPI'OVldQdlOH the rear side of 41. Flange Sdisprovidedwiththere: sp ective openings 57 and .58 .toper-mit alternateentry andexrtmpyemeng'as the casemay be,- betweenthe two flangegfor theright-hand and-left-nand locking-pins 5 as gear dl swingsithrough itsreference-position intone orthe other. The, positioningof-the lockingpins .may: ble made such. that no inner fiange SS is re quired.Thehtraek made bythe locking flanges insures that norotationofarmAS.on-shaft 33-may take place except as gear4l rotatessubstantiallyentirelythrough its. referencaposition;inone directionor the other,thatis, substantially -from-its attest position on oneside-of thereferenceposition tojtsatrest positionton theother side. of therefqrencfirpositie Reversalof movement of gear 41 when not in ,itsreferenceposition 'movement-sector does not change the-angnlanpositionof arm 45-relative. to th'qaxisofshaft. 33,0f.the. locking pins,54 oneof which is inside flange 56.

A switch shaftSfiis rotatably supported inabearing 60in bar 15,an d in;a,bearing. 61 .inplate .llhwhich bearings are respectively suitablybushedrand provided with a needle bearing... Atsleeve62tis keyed to-therear endiof switch. shaft 1 5.9 preventing, any V forward axial movementof the shaft 59. In addition, coupling shaft 27:: isalso suitablyconnegted for rotation ;to,. sleeve 62.:v Theforma mas ward endofrswitchsshaft 59Vis threaded for engagement by a.-nut-.63 which backs.up-athrust bear-ingu64. 'Thrust bearing 64 in turn bears against theclosed zendtofthe femaleportionofiofaa threaded coupling. ASShOWH inFigure 2 the closed end .of coupling 65'bears,against a'Washer-66 whichin turn is positionedaby ashoulder 67 on :shaft 59. -Hence,tl1efemaleportion 65 of thethreaded coupling is axially immovable relativeto shaft59 but may -be:rotated relative thereto. A'disc member ;68-isjourtnaled ton-shaft59 and hasan integral.forwardly extend- ,inghub- 69the-exterior ofwhiehzishelically threaded in ;.pitch and dimensioncorresponding to the threading of .theifemale portion 65. Disc member-68maybe moved .raxiallyovershaft 59 but eannotbe.rotated'relative tothe-axis of shaft 59 although shaft '59 ean-rotaterelative to member 68.Thus portions65 and 69 make-an-entire -threaded coupling.

'Adownwardly and rearwardlyextending lever arm 70 is integral withcouplingportion 65. .-A modified clevis -71 at the lowerend of arm 70has an opening 71a therein which surrounds rod 72. The diameterofopening71a is sufiicient to permit arcuate-movement of arm '70 rela- .tive tored 72. Registering :slots 73 :in thersides 'of theclevis, which are ofsufficientlength to permit the arcuate movement of arm 70, engagethe-ends-of a pin 74 which extend'thereinto. Pin 74 passesthrough andisafhxed to followerrod 72 .at thatposition 'along the length of rod 72at which a proper location of the axial movement of hub 69 along shaft59 -is.obtained. Follower rod -72 is axially movable ina-bracket'75which is bolted tobar .15. Properlybushed registering openings in .thesides 76 of. bracket 75 enable movementflofrfollower rod 72 to takeplace along its own axisand generally radially relative to cam 36. Aspring 77 presses arm 70 .downwardly, that. is inrclockwise directionasviewed'in Fig- .urevl, until and unless arm 70 is moved ina counter-.cloclcwisedirection byengagement of:cam.rise .36aand a roller 78fastened to the lowerrend .of rod'72.

.in .the embodiment shown in the drawings, the hub 69 is provided with aleft-hand thread. Therefore, vcounterclockwise movement ofarm 70 asviewedinvFig- ,ure 1 will shift disc .68 axially along switch shaft;59toward the front, that is, toward nut 63. On .the other hand, movementof arm 7 inia .clockwisedirection .tends to separate the parts (SS-69.ofthe threaded coupling and move disc 68 toward bar for a purpose whichwill be described. Suchmovement in a counterclockwise direction of arm76 as viewed in Figure 1 willvtake place when the roller 78 is engagedby cam rise 36a. 'When the rollerifi leaves cam rise 36a, spring'77 willreturnarm 70 to'its original position as shown in Figure 1. Thus, .theaxial movement of disc 68 in either direction-alongshaft 59 will bepositive and will minimize any tendency of the parts of a clutch 7910stick.

Clutch '79 comprises a frusto-conical male portion 36 which maybedesignated the 'drivenorrholding part and female portion 81 whichmayibedesignated the .drivingpart. Clutch portion '80 is inthe general'form ofan annulus which is provided with a bushing 82 which is'freely slidableand rotatable on switch shaft 59. A clutch plate 855 has afiixed to it apair of discs 84 of frictional material the conical peripheries of whichform the engagingsurface thereof. Sleeve bolts '85 slidablyextend'through bar 15, proper bushings againibeingprovided, and arescrewed into plate '83. Sleeve bolts 85 also'serve as guides for springs86 extending between the front of bar .ifi'and'the rear of disc 68.llBolts'f87 hold the forward end of the sleeve bolts 85 tightly againstdisc 63' around the axis thereof. Thus, springs '86 normally urgeholdportion '80 away from engagement with clutch part 81 to disconnect thetwo parts. In some embodiments the springs 86 will not .be necessary andreliance for disconnection may be placed entirelyronthe action ofcoupling 65-69. The influence of spring 77, which is powerfulthan thetotal force of springs =86, acts to .connect the two parts v,-81andrthereby holds part-.81..and shaft 59 immovable in .the manner of a.brakewheneverrod 72. isnnot in engagement with cam rise.. 36a. However,when arm 70 is lifted by cam rise :36a'thencoupling 65-69 tends toforeshorten and since portion 65 cannot move axially along shaft 59,disc 68 moves=forwa-rdly forcing clutch portion 80 out of connectiveengagement with clutchportion '81 freeing the latter for a snap action.driving movement of shaft 59.

Driving .portion 81 is the female part of the clutch 79 and hasan.interior:frusto-conical surface 88 adapted .to engage the\discs 84when. plate 83 is moved rearwardly along switch shaft 59. Member 81ispart of a casting orforged metalshape 89 which is immovably keyed toswitch shaftx59. .lnaddition, an integralcircumferential flange 96 onswitch shaft'59 fits into a corresponding recess. in sleeve 89 and isthere held .by thrust cap 91. Therearportion of;sleeve 89 is providedwith a circumferential gro.ove.92. .Symmetrically arranged around theaxis of switch shaft 59, thesides of the groove 92 normal to-the saidaxis are provided with opposed registering .pairsaof generally radialslots 93 extending to the outer edges .ofthe. groove-92. Each pair ofslots 93 engages :the trunnions 941of -a spring retainer'95respectively. In elevation these spring holders 95, as shown in Figures'4 to 6, for ;example,. generallyform a polygonal figure..Extendingthrough each retainer 95 from end to end thereof there is arod 96 positioned somewhat in the "manner .of a chord relative to gear'41. The ends of eachirod 96-fitinto corresponding recesses in cornerposts :97. Corner-postst97 in turniare'fastened by bolts 98 ,torthefrontsideofthe gear 41. The gear 41 is rotat-ably supported TOHFSWiiChshaft 59, a needle bearing'99, for example, being interposed.therebetween. A washer I 7160;maypbeipositioned.between the hub of gear41 and the .front .end of-bearing161.

when-thesnew mechanism .of this invention is at rest .or ;gear41is:momentarilyin-its dwell periodit may be in a position suehvasthatgenerally-shown in Figure 1. In that position hub-44 is in lockingengagementwith a saddle 43-Of-21-f00ih542 and theroller Idextendstowardcam-portion 3611- under the influence'of spring 77. Arm 70-therefore isin'itslowermost position and clutch parts 80-81-are connected holdingswitch shaft 59 against turning.

'slf an impulsezfrom the voltage regulating control circuit'is-received:causingmotor 18,'for example, to turn in one direction*orthe :otheryorif'such impulse is continuing, the shaft 33 will rotateand if continued'for a sufiicient length .of time, the roller 39 willengage that recess 4i; 'towar'd whichit is-approaching. Continuedmovement in 'thesame direction of shaft 33 will turn gear 41 in theoppositedirection to the direction'of' movement of shaft 33 through 'onesucceeding movement sector after the other until shaft 33 stops turningor is reversed in movementeausing'a reversal of movement of the gear 41.For each full 'revolution of shaft '33 the tooth 42 immediately abovethe shaft will be moved through a movement sector angle defined by theradii bisecting the saddle 43 of the tooth 42 immediately above-shaft 33and the saddle 43 of the adjoining tooth-42 moving toward shaft'33.Preferably adjacent the end of that movement sector, roller '78 will-beengaged'by cam rise 36a'raisiug arm 70 and disconnecting partsSii and S1of clutch 79 to permit sleeve 89-to snap the movable contacts 26 to thenext contact position. Meanwhilehub 4d will become engaged in loci:- ingrelation-with saddle 43 of the said adjoining tooth 42 which is now overshaft '33. "Clutch'79 will remain .disconnected until roiler 78againcornes opposite the cam fall portion 36b. in ordinary'operation,voltage regulation will involve one ormore steps in one directioninterspersed withone or more steps'in the'opposite direction dependingupon the conditionsin .the circuit being controlled.

As ,gear 41 is moved, for example, from the .position shown in Figure 4to the position shown in Figure 6, that is, through a sector ofmovement, thereby loading the spring retainers 95 to complete by snapaction a single step in the movement of contacts 26 relative to contacts24, the rods 96 compress the springs 101. The rods 96 are provided withshouldered portions 102 adjacent the extremities of each thereof. Hence,as the rods move under the influence of the movement of gear 41, thatshoulder 102a facing in the direction of such movement as illustrated inFigures 5 and 6 passes through an opening 103 in the adjacent end of thespring holder or box 95. As a shoulder portion 102 enters retainer 95the shoulder 102a will abut a piston 104 interposed between thatshoulder and spring 101, thereby compressing spring 101. A similarpiston 104 slidable in box 95 is interposed between the other end ofspring 101 and the other end of the box 95 for corresponding action inthe other direction when gear 41 is turned in the other direction.During the turning of gear 41 or at least during the initial stages ofthat turning, the clutch 80-81 prevents any rotation of hub 89 and thetrunnions 94 are held immovable except for such pivoting and sliding ofthem as takes place in slots 93 during the movement of the respectiverods 96 through bOXes 95. When follower rod 72 moves away from the axisof shaft 33 upon reaching cam rise 36a, the threadedcoupling 6569 willdisconnect portions 80 and 81 of the clutch 79. The springs 86 also actto disconnect clutch 79. Immediately, the springs 101, compressed asshown in Figure 6, will release their energy and through trunnions 94 ofspring holders 95 will snap hub 89 and thereby rotate switch shaft 59through the same movement sector angle with a corresponding snap,without any of the parts associated with shaft 33 or gear 41 beingcorrespondingly moved in any such snap action. The snap action rotationof switch shaft 59 in turn, as aforesaid, will through shafts 27 and 27aand their respective insulating coupling 32a move the movable contacts26 to the next contact position at high speed thereby minimizing arcingand interruption of current. In the event that the prime mover 18 shouldstop in the course of a movement sector before clutch 79 isdisconnected, the springs 101 will return gear 41 to its originalposition before the step began to await a further actuation in onedirection of the other. Seal-in switches may be used in the electricalcircuit of the new drive mechanism to insure against any suspension of avoltage regulation step after it has once begun and proceeded throughsome predetermined portion of the movement sector angle corresponding tosuch a step.

The symmetrical arrangement of the rods 96 and the spring retainers 95about the axis of switch shaft 59, gear 41 and hub 39 insures againsttroublesome stresses or dynamic imbalance in the operation of the newdevice. In addition, adjacent each end of each spring box 95 and spacedtherefrom there are provided openings 105. These openings in connectionwith whichever piston 104 in each retainer 95 is being moved, at thetime being, regulate the time-travel characteristic of the operation.

In the new drive mechanism each spring 101 preferably will beprecompressed or preloaded and will fill its entire box 95 when in an atrest or dwell position as shown in Figure 4. fter the springs arecompressed as illustrated in Figure 6, the disconnection of parts 80 and81 of clutch 79 to permit the snap action will cause the depressedpiston 104 in each retainer 95 to snap back, relatively speaking, towardthe adjacent end of the retainer 95. Once the respective piston 104 inso returning passes the openings 105 there will be a deceleration duringthe remainder of the travel of the respective spring boxes 95 therebycushioning the snap action and preventing shock to the parts so snapped.In such snapping, the hub 89 and hence the switch shaft 59 catch up withthe gear 41. If there is any tendency of the spring boxes 95 to overrun,that tendency will be substantially completely prevented by thepreloaded springs 101. In other words, when the springs 101 regain theiroriginal length as shown in Figure 4, renewed or continued movement of aprime mover is required to begin a new compression of the springs 101.

A conventional operation counter switch 106 having a contact arm 107 maybe mounted on bar 15 so that arm 107 engages the exterior periphery ofclutch part 81. That exterior periphery may be provided with a number oflands 108 equal in number to the number of teeth 42 on gear 41. Hence,each time oblique-surfaced coupling --69 passes through a holding andrelease cycle relative to the two parts of clutch 79 for each step ormovement sector, Geneva gear 41 will have moved an angular distance ofone tooth 42, and hub 89 and therefore lands 108 will have been snappeda distance of one land, thereby operating switch 106 once to enable itto cumulate the number of tap changes made.

A spring and spring retainer subassembly is illustrated in Figure 11. inthis subassembly a spring rod 96 is immovably mounted by its ends incorner posts 97 fastened to an intermittent-motion gear like gear 41. Aspring 101', preferably precompressed or preloaded, surrounds rod 96between the enlarged end shoulder portions 102 of rod 96. Springretainer box surrounds the spring 101 and annular end wall members 109fit into corresponding recesses in each end of each spring box 95'.Annular upstanding edges 110 of spring boxes 95' are crimped inwardlyover the end wall members 109 to hold them firmly in place. One or moreopenings extend through spring boxes 95 a predetermined distanceinwardly from each end. The size and number of these openings 105, likethe openings 105, will determine in part the speed-time snap actioncharacteristics of the new mechanism. An opening 111 extends axiallythrough each member 109 between the outer side of the ends of spring box95' and the outer face of respective pistons 104 adjacent thereto. Eachpiston 104' is provided with a hollow differential hub the outer portion112 of which closely surrounds shoulder 102 and the inner portion 113 ofwhich closely surrounds the narrower diameter of rod 96' on the otherside of the body of piston 104'. One or more openings 114 extend throughthe body of piston 104' from the inner face thereof to the interior ofthe aforesaid hollow hub. Shoulder 102a abuts a corresponding opposedshoulder on the inside of the hollow hub of piston 104 at the planeseparating the two portions 112 and 113.

The operation of the subassembly is similar to the operation asillustrated in Figures 4 to 6. Thus, if we assume that the left-handcorner post 97 under an actuating irnpulse is rotated to the right,spring retainer 95 in that portion of the step being held againstrotation, the left-hand shoulder 102a as viewed in Figure 11 will movethe lefthand piston 104' to the right shortening spring 101. If thesubassembly is immersed in transformer oil, for example, such oil willmove inside the spring retainer 95 between the inside of left-handmember 109 and the outer face of left-hand piston 104 through opening111. The movement of piston 104 will continue until the body thereofmoves inwardly past the opening or openings 105 at the left-hand end ofspring retainer 105, and right-hand piston 104 will slide inwardlyrelative to rod 96.

When the clutch corresponding to clutch 79 is disconnected, the spring101 will snap the right-hand piston 104' and thereby spring retainer 95'to the right as viewed in Figure 11 since right-hand piston 104' abutsagainst right-hand member 109. The interior shoulder of righthand piston104' will snap toward the right-hand shoulder 102a and any oil that mayhave accumulated between rod 96' and right-hand piston 104' will bevented through the openings 114 therein.

As spring box 95 snaps to the right, the left-hand piston 104 will moveto the left in a relative sense and the accelerating force will pass itsmaximum as when the lefthand piston 104 goes past the left-hand openingor openings 105. Thereafter the relative approach between left- 9 handpiston I04 and left-hand member 109 will-be principally governed by thediameter and length of the opening 111 until the parts are again inequilibrium at the end of the snap action. Movement of the parts in theother direction will operate in the same manner but in reverse.

Hence, in the snap action of the new drive mechanism of this invention,the parts thereof that are moved in the course of the snap actionreceived their maximum acceleration in the forepart or in anintermediate part of their travel and at the end of their travel theyare moving relatively more slowly. Thereby, a cushioning effect isachieved and substantially less shock results to the parts undergoingthe snap action. At the same time, the greater speed in the earlierportion of the snap action results in breaking of the are as thecontacts separate with lessened opportunity for pitting caused by thearc.

Various modifications may be made in the number, shape and size of theparts and in other details of the new drive mechanism of this inventionwithout departing from the spirit thereof or the scope of the appendedclaims.

I claim:

1. In a drive mechanism, in combination, a prime mover, anintermittent-motion gear driven by said prime mover, a switch shaftcontinually connected operatively to a movable contact member, meansproviding a constant resilient connection between said gear and saidshaft, movable means for holding said shaft substantially immovableduring at least a portion of the movement of said gear by said primemover, and means controlled by said prime mover for releasing said shaftto permit it to catch up with said gear under the force of saidfirst-mentioned means.

2. in a drive mechanism, in combination, a reversible prime moverresponsive to a change in electrical condi tions or the like, anintermittent-motion gear operatively connected to said prime mover, aholding device having a driving member and a holding member movablerelative to said driving member to permit engagement and disengagementthereof, a switch shaft continually connected operatively to a contactshaft, said switch shaft further being connected to said driving memberfor rotation therewith, means providing a continuous resilientconnection between said gear and said driving member, means forconnecting said holding member to said driving member during at least aportion of the movement of said gear, and means for moving said holdingmember to disconnect it from said driving member.

3. In a drive mechanism, in combination, an electric motor responsive toa change in voltage or the like, an intermittent-motion gear operativelyconnected to said motor, a holding device having a driving member and aholding member movable axially relative to each other to permitengagement and disengagement thereof, said holding member holding saiddriving member immovable when in engagement therewith, a switch shaftcontinually connected operatively to a contact shaft, said switch shaftfurther being rigidly connected to said driving member, resilient meansconnecting said gear and said driving n1ember, means urging said membersinto engagement to hold said driving member immovable during at least aportion of the movement of said gear, and means for moving said membersaxially away from each other.

4. In a drive mechanism, in combination, a prime mover responsive to achange in electrical conditions or the like, a rotatableintermittent-motion member operatively connected to said prime mover, aswitch shaft coaxial with said member and continually connectedoperatively to a movable contact member, a rod connected to said memberand disposed away from the axis thereof, a spring adjacent said rod inthe path of movement thereof, a retainer for said spring pivotallyconnected to said shaft, said retainer operatively engaging both ends ofsaid spring and coacting with said rod to compress said spring when saidmember is rotated and to provide a continuous resilient connectionbetween said member and said shaft, and

means to hold said shaft against movement during at least a portion ofthe movement of said member.

5. In a drive mechanism, in combination, an electric motor responsive toa change in voltage or the like, an intermittent-motion gear operativelyconnected to said motor, a brake having a driving member and a holdingmember, a switch shaft connected to said driving member for rotationtherewith, a movable contact member continually connected operatively tosaid switch shaft, said switch shaft being coaxial with said gear, meansrigidly connected to said gear, a spring engaging said means, a retainerengaging said spring, said retainer being pivotally connected to saiddriving member, means for connecting said holding member to said drivingmember to hold the latter immovable during at least a portion of themovement of said gear, and means for disconnecting said mem bars tocause said spring to turn said switch shaft.

6. In a drive mechanism, in combination, a prime mover responsive to achange in electrical conditions or the like, a rotatableintermittent-motion gear operatively connected to said prime mover, aswitch shaft coaxial with said gear, a movable contact membercontinually connected operatively to said switch shaft, a plurality ofrods mounted on said gear substantially in the form of a polygon, saidrods being generally equidistant from the axis of said shaft andsymmetrically arranged about the axis thereof, a spring on said rodsrespectively, a retainer extending between the respective ends of eachspring, said retainers being pivotally connected to said shaft, saidrods carrying means to engage said springs and coacting with saidretainers to compress said springs when said gear is rotated and toprovide a continuous resilient connection between said gear and saidshaft, and means for holding said shaft against movement during at leasta portion of the movement of said gear to cause the com pression of saidsprings.

7. In a drive mechanism, in combination, an electric motor responsive tochanges in voltage or the like, a rotatable member operatively connectedto said motor, a switch shaft, a compressing member connected to saidrotatable member, a box pivotally connected to said shaft, a spring insaid box, a piston slidable in said box, said piston being interposedbetween said compressing member and said spring, means for holding saidshaft against movement during at least a portion of the movement of saidrotatable member compressing said spring, and means for releasing saidshaft when said spring has been compressed to make said shaft catch upwith said member, the movement of said piston within said boxcontrolling the rotatational velocity of said switch shaft during atleast a portion of the movement of said switch shaft.

8. In a drive mechanism, in combination, an electric motor responsive tochanges in voltage or the like, a driving gear operatively connected tosaid motor, a driven gear engaged by said driving gear, said gearshaving different axes, a switch shaft coaxial with said driven gear, acompressing member connected to said driven gear in the manner of achord, a spring holder connected by trunnions to said shaft, a springbetween said member and said holder, means coaxial with said driven gearto hold said shaft against movement during at least a portion of themovement of said driven gear, and means coaxial with and actuated bysaid motor for controlling the operation of said last-mentioned means.

9. In a drive mechanism, in combination, an electrical motor responsiveto changes in voltage or the like, an intermittent-motion gearoperatively connected to said motor, a holding device having a drivingportion and a holding portion movable relative to each other to permitengagement and disengagement thereof, said holding portion holding saiddriving portion against movement when in engagement therewith, a switchshaft keyed to said driving portion, a movable contact continuallyconnected operatively to said switch shaft, means resiliently connectingsaid gear and said driving portion, means urging said holding portioninto engagement with said driving portion, said last-named meansincluding a coupling having complementary threadably engageable partsadapted when rotated relative to each other to disengage said holdingportion from said driving portion, and means for rotating said partsrelative to one another after a portion at least of a single movementstep of said gear has been made.

10. In a drive mechanism, in combination, an electric motor responsiveto a change in voltage or the like, a cam connected to said motor, anintermittent-motion gear operatively connected to said motor, a brakehaving a drive member and a hold member movable axially relative to eachother to permit engagement and disengagement thereof, a switch shaftconnected to said drive member for rotation therewith, means rigidlyconnected to said gear, a spring engaging said means, a retainer forsaid spring, one portion of a pivotal bearing rigidly connected to saidretainer and engaging another portion of said bearing in said drivemember, and means normally holding said hold member in engagement withsaid drive member, said last-named means including an oblique-surfacedcoupling actuated by said cam to move said hold member axially out ofengagement with said drive member.

11; ln a drive mechanism, in combination, an electric motor responsiveto a change in voltage or the like, at Geneva gear driven by said motor,a brake having a drive portion and a hold portion, a switch shaftconnected to said drive portion for rotation therewith, meanssymmetrically arranged on one side of said gear, a resilient memberconnected between said means and said drive portion, means to hold saidhold portion against said drive portion of said brake during at leastpart of the movement of said gear, means for disconnecting said portionsto permit said switch shaft to catch up with said gear, a rocking sectorarm engaging said gear on the other side thereof, a flange on said otherside to lock said arm in position until said gear passes through itsreference position, and a throw lever engaging said arm.

12. in a drive mechanism, in combination, a prime mover, a rotary plate,a spring, a spring box, means for holding said spring box againstrotation about the axis of said plate, means on said plate engaging saidspring, said spring box having an opening adjacent to and spaced from atleast one end thereof, a piston slidable in said spring box adjacentthat end thereof, said piston engaging said spring, and means forreleasing said first-mentioned means after said spring has been at leastpartly compressed by the rotation of said plate, whereby when saidspring box is released the "snap action thereof will attain its maximumspeed prior to the end of its travel.

13. In a high speed, snap action switch mechanism, in combination, areversible prime mover, a switch shaft, a plurality of stationaryelectrical contacts arranged in a circular path, a movable contactmember continually connected operatively to said shaft and arranged forsequential engagement with said stationary contacts, a rotatable memberengaging said prime mover, means resiliently connecting said rotatablemember and said shaft, means for holding said shaft substantiallyimmovable during at least a portion of the movement of said member bysaid prime mover, said resilient means including energy-absorbing meansfor retarding the speed of movement of said movable contact member as itmoves out of engagement with one of said stationary contacts and in adirect path into engagement with an adjacent stationary contact.

14. In a drive mechanism, in combination, a reversible prime mover, aswitch shaft, a plurality of stationary contacts arranged in a circularpath, a movable contact member continually connected operatively to saidshaft and arranged for sequential engagement with said stationarycontacts, and snap acting energy storage means including a lost motionmechanism between said prime mover and said shaft for driving saidshaft, means for holding said shaft substantially immovable during atleast a portion of the movement of said lost motion mechanism by saidprime mover, means actuated by said prime mover for releasing saidshaft, and an energy-absorbing device including a piston movable in afluid-filled cylinder for controlling the rate of movement of saidmovable contact member during at least a portion of its travel betweensaid stationary contacts.

15. In a drive mechanism, in combination, a reversible prime mover, aplurality of stationary contacts arranged in a circular path, a movablecontact member arranged for sequential engagement with said stationarycontacts, Geneva gear, intermittent-motion, energy storage meansccnnecting said prime mover and said movable contact member including arotatable driving member operatively connected to said prime mover, adriven member coaxial with said driving member and operatively connectedto said movable contact member, resilient means continually connectingsaid driving member and said driven member including a plurality ofsprings disposed symmetrically about the common axis of said members,and means for frictionally holding said driven member substantiallyimmovable during at least a portion of the movement of said drivingmember by said prime mover.

16. In a drive mechanism, in combination, a reversible prime mover, aswitch shaft, a plurality of stationary contacts arranged in a circularpath, a movable contact member continually connected operatively to saidshaft and arranged for sequential engagement with said stationarycontacts, snap acting energy storage means connecting said shaft andsaid prime mover for driving said shaft including an intermittent-motiongear operatively connected to said prime mover, means for frictionallyholding said shaft substantially immovable during at least a portion ofthe movement of said intermittent-motion gear by said prime mover, andmeans for locking said intermittent-motion gear in its position of rest.

17. In a drive mechanism, in combination, a prime mover, a rotatablemember operatively connected to said prime mover, a driven membercoaxial with said rotatable member, a movable contact operativelyconnected to said driven member, at least three resilient meanscontinually connecting said rotatable member and said driven member,each of said resilient means including an accelerating spring, saidsprings being disposed symmetrically about the common axis of saidmembers, and means to hold said driven member substantially immovableduring at least a portion of the movement of said rotatable member bysaid prime mover, all of said accelerating springs being loaded in thesame sense when said rotatable member is rotated relative to said drivenmember.

18. In a drive mechanism, in combination, a reversible prime mover, aplurality of stationary contacts disposed in a circular path, arotatable contact member arranged to sequentially engage said stationarycontacts, energy storing and releasing means between said prime moverand said contact member for driving said contact member, said meansincluding a reversible intermittent-motion gear resiliently connected tosaid contact member, said intermittent-motion gear having a referenceposition and being rotatable in both directions from said referenceposition, a reversing switch operable between a first and a secondposition, means for operating said reversing switch from one of saidpositions to the other when said intermittent-motion gear is movedthrough its reference position, and means for locking said reversingswitch in either of said positions selectively when saidintermittent-motion gear is away from its reference position.

19.In a drive mechanism in accordance with claim 18 wherein said meansfor locking includes a pair of con centric circular flanges on saidintermittent gear and said reversing switch includes a member pivotablebetween a first and a second position, and a control pin on saidintermittent-motion gear for operating said member from one to the otherof said positions, said member having finger portions engageable betweensaid flanges to lock said member in either of said positionsselectively.

20. In a tap changing mechanism having a reversible prime moverconnected by energy storage and releasing means including anintermittent-motion gear to a movable contact adapted to sequentiallyengage a plurality of contacts arranged in a circular path, saidintermittentmotion gear having a reference position and being rotatablein both directions from said reference position, the combination withsaid intermittent-motion gear of a pair of concentrically arrangedcircular flanges on said gear, the outer of said flanges having spacedentrances, a pivoted member having a pair of spaced fingers eachdisposed adjacent an entrance in said outer flange, said fingers beingmovable alternately through the spaced entrances to a position betweensaid flanges as said memher is pivoted, a control pin on saidintermittent-motion gear engageable with said pivoted member when theintermittent-motion gear is in its reference position to pivot saidmember in either of two directions to move one of said fingers into theentrance adjacent thereto, and a reversing switch actuated by saidpivoted member.

21. A tap changing mechanism in accordance with claim wherein saidreversing switch includes a pair of spaced stationary contacts, a shaft,and a movable contact connected to said shaft and arranged toalternately engage said stationary contacts, said shaft having aradially extending arm connected to said pivoted member and beingadapted to operate said movable contact into engagement with either ofsaid spaced stationary contacts selectively when said arm is actuated bythe pivoting of said member.

22. A tap changing mechanism in accordance with claim 21 wherein a lostmotion connection is provided between said arm and said pivoted member.

23. In an electrical switching mechanism of the step type in which amovable electrical contact is moved with rapid motion out of engagementwtih a fixed first electrical contact and into engagement with a fixedsecond electrical contact, a spring-driven operating means for movingsaid movable electrical contact, said means comprising a spring and anenergy absorbing device operatively connected to said operating means toretard the speed of movement of said movable contact as it moves fromsaid first contact to said second contact, said energy absorbing deviceincluding a plunger movable in a fluidcontaining dashpot.

24. In an electrical switching mechanism of the step type in which amovable electrical contact is moved with rapid motion out of engagementwith 'a fixed first electrical contact and into engagement with a fixedsecond electrical contact, a spring-driven operating means for movingsaid movable electrical contact, said means in- 14 eluding a spring andan energy absorbing device continually operatively connected to saidoperating means and opposing said spring to thereby retard the speed ofmovement of said movable contact as it moves in a direct path from saidfirst contact to said second contact.

25. In an electrical switching mechanism of the step type in which amovable electrical contact is moved with rapid motion out of engagementwith a fixed first electrical contact and into engagement with a fixedsecond electrical contact, a spring-driven operating means for movingsaid movable electrical contact, said means including a spring and anenergy absorbing device operatively connected to said operating means toretard the speed of movement of said movable contact as it moves fromsaid first contact to said second contact, said energy absorbing deviceincluding a piston movable in a liquidcontaining cylinder having aliquid relief aperture.

26. In an electrical switching mechanism of the step type in which amovable electrical contact is moved with rapid motion out of engagementwith a fixed first elec trical contact and into engagement with a fixedsecond electrical contact, a spring-driven operating means for movingsaid movable electrical contact, said means including a spring and anenergy absorbing device operatively connected to said operating means todecrease the speed with which said movable contact moves into ongagementwith said second contact, said energy absorbing device including apiston movable in a liquid-containing cylinder having a liquid reliefaperture disposed at a point intermediate the two positions of extrememovement of said piston in said cylinder.

References Cited in the file of this patent UNITED STATES PATENTS780,496 Elers Jan. 24, 1905 998,953 Capwell July 25, 1911 1,038,990Trefry Sept. 17, 1912 1,047,277 Nichols Dec. 17, 1912 1,803,653 Rah May5, 1931 2,009,383 Blume July 30, 1935 2,107,373 Edwards Feb. 8, 19382,177,109 Hill Oct. 24, 1939 2,253,183 Le Count Aug. 19, 1941 2,267,394Butler Dec. 23, 1941 2,480,589 McKenney Aug. 30, 1949 2,605,647 DuvoisinAug. 5, 1952 2,693,573 Perkins Nov. 2, 1954 FOREIGN PATENTS 382,656Great Britain Oct. 31, 1932 629,650 Great Britain Sept. 26, 1949

